Treatment of hydrocarbon oils



oct. 25, 1982. J. D. SEGUY` 1,884,887

TREATMENT OF' HYDROCARBON OILS Filed Jan. 1o. 1929 2 sheets-snaai 1.

@88 wfb Q4 M@ N a E# 8 L* `N 88 oct. 25,l 1932. J, D. SEGUY y 1,884,887

TREATMENT OF HYDROCARBON OILS Filed Jan. 10. 1929 8 shetsfsheet 2 e072 tZ7. 5e

Patented Oct. 25, 1932 UNITED STATES PATENT OFFICE JEAN D. SEGUY, OF CHICAGO, ILLINOIS, ASSIGNOR TO UNIVERSAL OIL PRODUCTS COH- PANY, 0F CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOT TREATMENT OF HYDROCARBON OILS Application filed January 10, 1929. Serial No. 331,436.

This invention relates to the treatment of hydrocarbon oils by heat for the Aproduction of light valuable distillates, by means of processes wherein cracking may take place either as a primary or secondary object. The feature of the invention may be applied, for instance, to a type of process, among o hers, where the oil is heated to elevated te eratures in a heating zone, such as a Coil, then transferred to an enlarged zone where separation of vaporized from unvaporize'd products, with or without accompanying reaction, may occur; where the vapors may be removed from such enlarged zone, and thereafter subjected to dephlegmation and Where the vapors remaining uncondensed after dephlegmation are condensed and collected, after separation from the so-called non-condensable gas, in the form of lighter distillates, motor fuels, or gasoline-like products. In such type of process, vapors condensed in the dephlegmator may or may not be returned to the process for further treatment and the unvaporized products separated in the enlarged zone may he removed therefrom without bein returned to the heating zone.

In the operation of such processes, Whether used principally for cracking or Where cracking'takesplace as a secondary action, it has been proposed to maintain the heating coil and the enlarged zone under substantially the same superatmospheric pressure, and it has also been proposed to maintain the heating coil under superatmospheric pressure and the enlarged zone under a reduced pressure. `It has also been proposed, particularly for socalled vapor phase cracking, to use relatively low superatmospheric or substantially atmospheric pressures on the entire process.`

In these processes, the pressure maintalned on the vapors produced While they are subj ected to dephlegmation may be substantially the same as, or relatively lower, than that maintained on the enlarged reaction or separating zone, although still above atmospheric, or it may be substantially atmospheric pressure.

In order to condense the gasoline-like or lighter condensable materials and separate them from the non-condensalole gases after dephlegmation, it has been proposed, in some processes, to rectify this entire mixture of non-condensable gases and condensable vapors, including every fraction thereof from the lightest fractions to the heaviest ones entering into the composition of said non-condensable gas and gasoline-like or light distilla'te, said vaporous mixture entering the rectification zone at a temperature correspending approximately to the boiling points of the heavier fractions of the mixture under the pressure used.

In other types of processes it has been proposed that this condensation and separation of the vapors and incondensable gases after dephlegmationbe effected, first, by condensing the condensable materials and cooling the mixture to approximately atmospheric temperature, thereafter passing the materials remaining uncondensed and separated from the liqueed fractions to a rectifying cr so-called vapor recovery zone.

The proposed types of processes just Elde-v scribed have disadvantages when compared to some of the features of the process of the present invention. The process of the present invention, in some of its features, proposes to effectrectiiication or condensation of the gasoline-like or lighter liqueiable products, and their separation from the gases in such manner that substantially no, or comparatively little, gas Will be Withdrawn in solution in the liquefied fractions after separation has taken place. It also proposes that the rectification of non-condensable from condensahle fractions, to sharply separate them into light liquid hydrocarbons and relatively dry gas, be effected on a mixture of the non-condensable gases produced and of only the lighter portions of the liquefiable gasolinel or light vapors removed from the dephlegmating zone of the process.V

It is to be understood that when reference is made to uncondensable or liqueable materials, this is to be taken in relation with the state of these materials when at atmospheric pressure and ordinary temperatures.

Returning now to the various processes heretofore referred to, wherein the features of this invention may be used, and more articularly to such processes where cracklng is permitted to take place, as a primary purpose, it is generallyrecognized that the phenomena of cracking ma be divided into two phases-one, the so-ca led splitting reaction, whereby smaller molecules are formed, and the other, the so-called polymerizing reaction, forming larger molecules than those contained in the original oil, and proi ducing, if carried too far, objectionable amounts of so-called sludge or coke, which are undesirable products of a cracking operation. y I

Owing to some of the features of this invention, the cracking reaction is so controlled as to get a maximum amount of the so-called splitting phase of the reaction and a minimum amount of the so-called polymerizing phase; bythis process of controlled pyrolysis I have found that the amount of coke or sludge formed can be reduced from a very large amount to an amount which may be as small as one-iiftieth of the amount ordinarily formed if the reaction is not controlled as herein described.

According to one of the methods of prac- L)ticing this invention, I referably control the degree of reaction obtained in the heating zone or coil, dependent upon the time ele.- ment and temperature and pressures used, by inserting, on 'the end of the coil, a valve, by means of which I reduce the' pressure from that used in the coil to a much lower pressure at precisely the right time, so that the oil as delivered from the heating zone is reduced from its high pressure to a lower pressure, thereby cooling the oil by vaporization and checking the reaction at about the time at which the objectionable polymerizing ghase of the cracking reaction would begin; t ereby substantially reventing the formation of undesirable collie and sludge. I have also found that, after having obtained in this manner a controlled pyrolysis of the hydrocarbons in the heating zone, it is necessary to control the rate of withdrawal from the process of the heavier unvaporized oliquid products which result from such controlled pyrolysis and which accumulate in the enlarged zone of reduced pressure. This rate of withdrawal will depend upon the degree of pyrolysis obtained inthe heating zone, the

' degree of reduction of pressure between the heating zone and the enlarged zone, the temperature maintained or obtained in the latter, and upon the maximum tolerance for the formation of sludge and coke.

It may be necessary that in an apparatus used to carry out the invention, the rate of withdrawal of the heavier liquid products from the enlarged zone be such that the level of such unvaporized products be maintained at a low point in said zone.`

I have found thatV diierent oils require a different combination of time, temperature in the heating zone, pressure drop at the disJ charge of the heating zone, and rate of withdrawal to' get the best results desired.

It will be understood that when the oil is passing from the heating zone through a valve to a zone kept at a much lower pressure than the heating zone, two cooling effects may be obtained. One of them is that due to the expansion of the heated mass on reduction from a high pressure to a low pressure'which is known as the J oule-Thompson effect, and the other may be the cooling effect due to the passage of the oil from the heating zone to the zone into which the oil is discharged at a low pressure, which zone may not be heated by external means, and from which the products are rapidly withdrawn.

, A modified method of operation may be Acarried out as follows:

I may treat the oil in the heating zone and the enlarged zone without the interposition of a valve between said zones, maintaining substantially the same pressure in both, which may be atmospheric pressure or above. In an operation of this character, I may obtain a controlled pyrolysis of the hydrocarbons by proper control ofthe temperature towhich the oil is subjected in the heating zone, or the rate at which the oil passes through the apparatus, or the pressure maintained on the heating and enlarged zones,

and the rate of withdrawal ofthe unvaporized liquid products separating -in the enlarged zone, and by a proper balance between these factors.

In some instances, when producing liquid residues from the process, the proper balance maybe indicated, when the desired yield of lighter products from the operation is being obtained, by the content of sludge in the unvaporized products'removed from the enlarged zone. This content should be, in all instances, below the maximum allowed, which may be around 5% but preferably around 2%,based on the liquid products removed from said zone.

When comparing two operations carried out in the heating zone or coil and enlarged zone according to the alternative methods described, where every condition remains the same, except that in one operation the-pressure is reduced at the end of the coil, while in the other it is not, the operation where the pressure is reduced at the end of the heating coil, because of the drop of temperature accompanying the pressure reduction,vmay permit of maintaining-the unvaporized products in the enlarged zone ,a longer time than the other operation, before the same degree lof polymerization is obtained.

Returning to the features of the invention which concern the treatment of the vapors and gases separated in the enlarged zone from the unvaporized products of reaction or distillation, this phase of the invention may be carried out in processes where, as a result of the reduction of pressure between the heating zone and the enlarged zone, the following dephlegmation, separation, and recovery of the lighter products are necessarily carried out at relatively low super-atmospheric or at substantially atmospheric pressure. This phase of the invention is also applicable to processes wherein the pressure on the heating and enlarged zones is equalized and varies from substantially atmospheric to a high degree of superatmospheric pressure; the pressure on the dephlegmating and subsequent vapor treating zones may therefore vary from substantially atmospheric to a high superatmospheric pressure; in such processes it may be desirable, however, to maintain the pressure on the said last named zones at a substantial'atmospheric or a relatively low super-atmospheric pressure, even if to do so it is necessary to reduce the pressure on the vapors leaving the enlarged zone,

relative to the pressure used therein.

The dephlegmation or rectification of hydrocarbon vapors is easier and cheaper as the pressure used is lowered. At lower pressures 1t is possible to make sharper separation between condensed and uncondensed materials than at higher pressures, because the vapor pressure curves of the constituents are farther apart at low than at high pressures.

It may also be advantageous to use low ressures for dephlegmation and rectification insofar as the cost of the material and operation is concerned.

However, the use of relatively low superatl mospheric or substantially atmospheric pressure on the dephlegmating, condensing and separating zones, employed in processes herein referred to, has some disadvantage when compared with processes where these` operations are carried under higher pressure. This resides in the fact that when the non-condensable fractions are separated from the liquefied fractions removedl therewith after cooling to ordinary temperatures, the socalled non-condensable gases carry with them valuable lighter 'condensable hydrocarbons in a quantity which increases as the pressure under which the separation is eifecteddecreases.

On the other hand, the liquefied portions separated from non-condensable gas, after cooling to ordinary temperatures, car dissolved with themsubstantial quantities of non-condensable gases; n this quantity increases as the temperature of separation decreases, and as the pressure under which the' separation is effected increases.v

Some of the features of my process hereafter described, eliminate or substantially decrease the disadvantages of heretofore proposed processes independently of thepressure under which dephlegmation, condensation, and rectification are carried out.

The ease and efficiency with which rectification processes may be carried out for sharp separation of two fractions depends primarily upon the difference between the vboiling points of these two fractions under the conditions described. In a mixture of hydrocarbon vapors, the higher the boiling points of the fractions considered, 'the closer a-relthe boiling points of the individual hydrocarbons which make up the fractions. For instance, in the lighter or low boiling point portions, generall called non-condensable gas, the difference etween the boiling points of some of the constituents thereof may amount to approximately 35 degrees F. or more. As one considers a heavier or higher boiling fraction, the boiling points of the pure hydrocarbons constituting such fraction become closer together, and in heavier fractions having a boiling point range between, say, 400 and. 450 degrees F., the difference between the boiling points ofthe pure hydrocarbons entering the composition of these fractions may only amount to a few degrees F.

I have found that it is unnecessary and wasteful on the efficiency and cost of the oper` ation to include, in a rectification process for sharp separation of so-called non-condensable gas from gasoline-like products, the heavier fractions of the vapors which, after condensation, will enter in the composition of the gasoline-like or light liquid products from the process.

Therefore, according to one of the features of the invention,-the mixture of non-condensable gases and vapors produced in the distillation and/or conversion of hydrocarbon oils may be removed from the dephlegmating zone of the process at such temperature under the pressure used, that their end point corre-- sponds. for instance, approximatelv to the end point of gasoline-like or other light liquid products. This vaporous mixture is then subjected to partial condensation and cooling, under the pressure at which the de- .phlegmation was effected, or under a different pressure, down to a temperature above the prevailing atmospheric temperature. Such partial condensation and cooling is so controlled that only the heavier' portions of the vaporous mixture are condensed, still leaving in vaporous form the incondensable gas and lighter vapors of the mixture. These condensed heavier fractions are removed from the process, and the remaining mixture of lighter condensable vapors and non-condensable gases is subjected torectification for sharp separation of the liqueiable fractions from the non-condensable gases, the latter in the form of substantially dry gas. Said lighter liqueable fractions condensed during rectification may thereafter be combined with or kept separate from the heavier vaporous fractions subjected previously to partial condensation, to form commercially useful products having the character of'gasoline or other useful light hydrocarbonmaterials.

T he object of this feature of the invention is to avoid the unnecessary rectification of the heavier'fractionsof the vapors removed from -the dephlegmating zone, and, therefore, ob-

tain considerable improvement over such v processes heretofore referred to, which propose subjecting heavier and lighter vapors and gases together to rectification, and wherein rectification of the heavier fractions decreases. the eiiiciency'and increases the cost of the operation without improving the separation of the liquefiable hydrocarbons from the so-called non-condensable gases.

The process of the invention also possesses 'considerable advantages over processes here'- tofore decribed where the vapors and noncondensable gases removed from the dephleglmation zone are cooled to a temperature approximating atmos heric before separation and rectification. n such processes, the liquefed vapors separated from the gas at ordinary temperatures carry non-condensable gases in solutionout of the separation zone 1n an amount which, every condition remaining the same, depends upon the temperatures at which the separation is effected, and decreases lrapidly as this temperature increases.

Therefore, the partial condensation and cooling of the gas and vapors down to a temperature substantially above atmospheric and the separation of the condensed heavier distillate from the remaining gas and vapors at that point, according to my invention, results in materially reducing the quantity of gas carried out by the distillate at that point, relative to the quantity carried out at ordinary temperatures. This advantage is due to the smaller quantity of fractional distillate removed at that point, and primarily to the decreased solubilityv of the gas in the distillatev on account f the higher temperatures.

sequent gas release or evaporation in separating or storage tanks, and decreases materially the cost of recovery of such light valuable fractions.

In short, some of the features of the process of the invention consist in fractionally condensing or' dephlegmating hydrocarbon vapors to form a mixture of so-called nonlcondensable or fixed gas and conden'sable vaypors having an end point a roximatel that of the useful pp y product desired from theopera tion of the process, then taking this mixture and partially condensing and cooling it to temperatures above the prevailing atmospheric temperature, to liquefy only the heavier fractions of the condensable vapors, separating these liquefied heavier fractions from the non-condensed fractions and then subjecting the non-condensed fractions, including non-condensable gas, to rectification for the 'separation of the lighter condensable fractions from the non-condensable gases in as dry a form as possible. Y

The removal, from the materials sent to rectification, of the heavier liquefiable fractions considerably improves the facility with which the rectification may be effected, at the same time decreasing the investment and the operating expenses required therefor.

Other features of the invention will be apparent from the following description of the process, and, for illustration, I have shown in the drawings attached,r various forms of apparatus in which this mvention may be carried out.

Fig. 1 shows a diagrammatic sketch, in no sense to scale, of an apparatus which may be utilized in carrying out the invention.

Fig. 2 shows. a modified form of apparatus which may be used. This drawing` is only diagrammatic and not to scale;

It is to be understood-that whenever reference is made to boiling points, the figures given are the boiling points of the material when considered under atmospheric pressure.

Referring to Fig. 1, and to an illustration of an operation which may be carried out in the apparatus shown therein, the oil to be subjectedto treatment may be drawn from storage tanks through pipe 1 and forced bg means of pump 2 into feed line 3 from whic lit enters the heating coil 4. The heating-coil 4 is positioned in a furnace '5 of any conventional type The oil is heatedin the coil .to the temperature required for the treatment,

and discharges therefrom through line 5', in

which may be interposed valve 6, into an enlarged drum 7 in which separation of heavier unvaporized liquid residue from lighter vaporized products takes place. The unvaporized liquid residue may be withdrawn from drum 7 through residue drawoif line 8, controlled by valve 9 and directed to further treatment or to Astorage through'line 10. The vapors separated in drum 7 may be removed therefrom through line 11 hav-ing valve 12 and directed to dephlegmating, fractionating, or rectifying zone 13, which is provided with any conventional means suitable for' such operation. Cooling means at the upper portion of zone 13.1and heating meansy at the ottom of saidzone may be provided to effect a proper degree of dephlegmation desired n.through heat interchange with cooling and heating agents, in direct or indirect contact with the vapors undergoing dephlegmation. These temperature regulating agents may be' `through line 18 by proper manipulation of valve 19 on said line and valve 20 on line 3.

Heavier portions of the vapors from the .process are dephlegmated and condensed in dephlegmating zone 13l` and this condensate, depending upon the purpose of the treatment, may be withdrawn from the dephlegmating zone 13 through line 21 and thence returned to the charging line 3 through line 22 in which may be interposed valve 23 and hot oil pump 24; or this condensate may be removed Jfrom the system and sent to storage or to treatment elsewhere through line 25 in which is interposed valve 26. Or, by suitable' regulation of valves 23 and 26, any desired portion of this condensate may be withdrawn from the system while the other portion is returned to the heating tubes 4.

The vapors and gases remaining uncondensed in dephlegmation zone 13 may be removed from the top thereof through line 27 in which may be interposed valve 28, and may thenbe passed through condenser cooler 29 wherein they may be subjected to partial condensation and cooling, as heretofore described, in such manner that only the heavier portions of these vapors are liquefied while passing through said condenser. The mixture of heavier distillate and lighter uncondensed vapors and gases leaving the condenser 29 may discharge into hot separator 30. The condensed portion may be removed therefrom through line 31 in which are interposed valves 32 and 35. and sent to storage or further treatment. If desired, it may also receive additional cooling down to atmospheric temperature in cooler 33, positioned on a by-pass from line 31 and controlled by valves 34. This heavier distillate may afterwards be mixed with those fractions of the vapors separated in hot separator 30 which willv be liquefied during rectification as will be hereafter described. and the mixture thus obtained may then be directed to treatment or to storage.

Returning to the lighter fractions of the vaporous products withdrawn from dephlegmator 13'which remain uncondensed after passage through partial condenser 29 and separation from the heavier distillate in the hot separator 30, they may be removed from the latter through line 36 in which is interposed valve 37. 'Line 36 may also be provided with a by-pass 38 in which may be interposed valves 39 and pump 40 which may be cut into the apparatus. This mixture of uncondensed lighter vapors and gases is thus dirccted to stabilizing or rectifying zone 41. which latter may be provided at the bottom and at the top, respectively, with Suitable' well known heating or reboiling and cooling means such as illustrated at 42 and 43. There the uncondensed vapors and gases from the process are separated sharply into a condensed lighter distillate and substantially dry mixture of gaseous and unstable hydrocarbons. These may be withdrawn from the top of the stabilizing or rectifying column 41 through line 44, provided with valve 45. The condensed and rectified lighter distillate may be removed from the bottom of zone 41 through' line 46, provided with valves 47 and 50 through which it may be directed to storage or further treatment separately; or such lighter rectified distillate by the use of branch 48, provided with valve 49, connecting discharge lines 31 and46, may be mixed in suitable proportions with the heavier distillate resulting from the partial condensation in condenser cooler 29, and the mixture may then be directed to further treatment or to storage. U

Now referring to Fig. 2, I have shown a modified form of apparatus which may be used in connection'with oil treating apparatus such as shown in Fig. 1, but in lieu and place of the partial condensing and rectifyy ing parts shown in Fig. 1.

In the use of this modified apparatus, the vapors remaining uncondensed in dephlegmating zone 13 may be removed from the top thereof through line 27 having valve 28 and may be passed into a rectifying zone 101 provided with upper cooling means 102 and 10W- er heating means 103. There the temperature is so controlled that the condensable vapors and uncondensable gases, removed from dephlegmating zone 13 through line 27, may be partially condensed as heretofore described. The condensed heavier fractions may then be withdrawn from the bottom of rectifying zone 101 through line 104 having valves 105 and 120 and directed separately or in admixture with lighter materials to storage or further treatment. with or without additional cooling down to ordinary temperatures. The uncondensable gas andlighter fractions from the vapors withdrawn from dephlegmating zone 13, and which have not been condensed' -vided with valve 107 and with by-pass 108,

controlled by valves 109. in which is interposed vapor pump 110. Through line 106, or

through the by-pass 108, these uncondensed materials may pass into a stabilizing or rectifving zone 111 wherein sharp separation is eiected between the lighter condensable material and the uncondensable gases. This rectifying zone 111 is provided with bottom heating means 112 and upper cooling means 113. The substantial dry uncondensable gases may be withdrawn from the top of stabilizing or rectifying zone 111 through line 113', having 'valve-114, and may be directed to further lightdistillates, which may then be directed lto further treatment or to storage.

Without further describing in detail other modified forms of apparatus which may be used to carry the features of this invention,

.I may mention that dephlegmating zone 13 of Figs. 1 and 2 may comprise one or more dephlegmators, or that the fractions which may be separated by condensation therein, to produce from the dephlegmating zone vapors having the desired end points, can be removed as one or more separate streams of varying characteristics. When the dephlegmating zone comprises for instance, two dephlegmators, thev vapors from enlarged zone 7 will then be subjected to a series of ldephlegmations. The condensate from the first dephlegmator may be returned to the heating coil for treatment, or removed separately and the vapors from said dephlegmator may pass through the second dephlegmator. In said second dephlegmator, the condensate produced therein may be separately evacuated to storage or `subjected to treatment, and the vapors from said second dephlegmating zone may then pass to the rectification zone, including the step of partial condensation, shown at 29, 30 and 41 in Fig. 1 and at 101 and 111 in Fig. 2, for the vapors leaving dephlegmating zone 13 shown in said figures.

The operation of the processes described with the types vof apparatus referred to herein is preferably so regulated that the vapors entering the artial condensing zone, such as zone 29 in ig. 1 and zone 101 in Fig. 2y have an end boiling point corresponding nearly to the end boiling point of motor fuels or light distillates, such as gasoline.

As an illustration of a method for operating some features of this process, vapors and uncondensable gas entering the partial condensation or rectication zone through line 27 may be at such temperature, under the pressure used, that will ve material having an end boiling oint o about 420 to 440 degrees F. at atmosp eric pressure.l Then 1n partial condensation and separation zones 29 and 30 of' Fig. 1, or in rectifying zone 101 of Fig. 2, this material may be subjected to partial condensation or rectication, -at a temperature under vthe pressure used, such that the bulk of the material condensed and withdrawn through line 3101' through line 104 may begin to boil, at atmospheric pressure, at a temperature of 200 degrees F., more or less. The amount of material boiling below 200 degrees F. left in this heavier distillate will depend upon the sharpness of the separation obtained in this partial condensation or rectification step. In this manner, the material left uncondensed in separator 30 of Fig. 1 and in rectifier 101 of Fig. 2 may be composed of hydrocarbons, the bulk of which will have boiling points lower than approximately 200 degrees F., at atmospheric pressure. This uncondensed material is then passed into the stabilizing or rectifying zone 41 of Fig. 1 or 111 of Fig. 2, where the temperature is such that the material condensable at atmospheric pressure and ordinary temperatures is separated from the so-called uncondensable gases. The material condensed therein and withdrawn through pipes 46 or 115 will thus have an end point of aproximately 200 degrees F. more or less.

his lighter distillate may then be blended with the heavier distillate withdrawn through line 31 or line 104 in suitable proportions to constitute a gasoline-like motor fuel which may correspond to specification land which may have an end boiling point of about 437 degrees F.

In another method of carrying out the invention, these two streams of heavier and lighter distillates may be kept separate. The stream of heavier distillate having boiling points at atmospheric pressure between about 200 and 450 degrees F., as heretofore described may be kept separate and sold or utilized as naphtha or otherwise, while the stream of lighter distillate withdrawn from stabilizing zone 41 or 111 may be utilized by blending with suitable material for the manufacture of high grade aviation gasolines having end boiling points, at atmospheric pressure, of approximately 325 degrees F.

It is to be understood that the conditions heretofore given as illustrations are not to be understood as limiting the invention and that the temperatures at which the separation is effected in the partial separation or rectifying zones 101 of Fig. 2 or 30 of Fig. 1 may be varied over quite a wide range, preferably between temperatures of, say, 140 degrees F., more or less, and 300 to 325 degrees F. more or less. an operation at atmospheric pressure and if pressure is employed, the temperatures just given will have to be raised to correspond with the increase in boiling points of the hydrocarbons, due to the increase in pressure.

The partialcondensation or rectification zone 30 or 101 and rectifying zone 41 or 111 of' Figs. 1 and 2, respectively, may be maintained at substantially atmospheric pressure or superatrnospheric pressures, and if it is desired to maintain either one or both of these Zones under a pressure higher than that pre- These temperatures are given for vailing on the vapors, entering said zone, vapor pumps or compressors may be interposed on the lines in order to` maintain the desired pressures.

As an illustration, this operation may be carried out in connection with a process Where hydrocarbon oils are cracked under high temperatures and pressures by being passed through heating coil 4 and being raised therein to a temperature of approximately 900 degrees F., more or less under a pressure which may be, say, approximately' 500 pounds, said pressure being reduced by means of valve 6 to approximately 80 pounds on chamber 7. The conditions of time element in said coil and chamber may be such that under the temperatures and pressures used therein, the residuum withdrawn from chamber 7 through line 8 contains less than 5% and preferably less than 2% sludge as'measured by benzol centrifuge. The dephlegmating and rectifying zones connected to Ychamber 7, as hereto- I fore described, may be maintained substantially under the same pressure as chamber 7 or under a lower pressure. By the use of vapor pumps shown, or by the interposition of vapor pumps (not shown) at proper points, as Well as by the use of the valves shown on the Avarious lines, any suitable decreasing or increasing differential pressures may be maintained, if desired, on the various parts of the process between dephlegmating zone 13 and the inalrectifying or stabilizing zone 41 or 111.

The process may also be carried out under such conditions as will cause so-called vapor phase cracking, or it may be so operated that While cracking takes place in the operation, it is a secondary object thereof.

Depending upon the purpose of the operation and Whether cracking is a primary or secondary object thereof, the reux condensate from the dephlegmator 13 or, when a series of dephlegmating zones is utilized, one orl more streams of reflux condensate, may be returned to the heating tubes for retreatment; or no reflux condensate may be permitted to return to the heating zone for retreatment, the stream or streams being then sent to storage or separate treatment. Further, dependent upon the same factors, the temperatures and pressures utilized in the process will be varied, 'the temperatures and pressures given above in the operations illustrated being in no Way limitative of the scope of the processes in which the features of this invention may be utilized.

The partial condensing, rectifying, and gas separating phase of this invention has particular utility and advantage of adaptation when it is used for treating oil in connection with a process of the so-called tube and tank type, v vherein a large differential in pressure 1s maintained between the heating coil or tube and the enlarged tank, whether crack- Athe condensed heavy ing is the primary or a secondary' object of the treatment. In such process the differential in pressure is most advantageous to the production of comparatively large yields'of motor fuels with aminimum comparative formation of coke and sludge. On the other hand, it inherently tends to increase the loss of fractions of these motor fuels with the gases. This latter disadvantage can oiilybe balanced by providing in combination with the heating' and reacting part of the process, costly and intricate rectifying apparatus, which, according to the methods heretofore used in their operation, did not provide for ythe vapor-gas mixture, and then rectifying the mixture in the absence of said condensed heavy gasoline cut to sharply separate and condense said lighter gasoline cut from the incondensable gases.

2. A method for treating the vaporous and gaseous mixture produced in the cracking of hydrocarbon oils which comprises dephlegmating the mixture of vapors and gases to condense and separate therefrom fractions heavier than gasoline, then subjecting the mixture to partial condensation at a temperature above atmospheric, to condense therefrom a heavy gasoline cut While retaining a lighter gasoline cut in vapor form, separating gasoline cut from the vapor-gas-mixture, in introducing the mixture to the lower portion of a rectifying co1- umn which is heated at the bottom and cooled at the top and wherein the vapors and gases rise countcrcurrent to descending condensate formed therein, and rectifying the mixture in said coumn in the absence of said con-I densed heavy gasoline cut to sharply separate and condense said lighter gasoline cut from the incondensable gases. V

3. A method for treating the vaporous and gaseous mixture produced in the cracking of hydrocarbon oils which comprises dephlegmating the mixture of vapors and gases to condense and separate therefrom fractions heavier than gasoline, subjecting the mixture to partial condensation in a mamier to condense therefrom the gasoline hydrocarbons boiling above approximately 200o F. at atmospheric pressure, while retaining in vapor form the gasoline hydrocarbons boiling below approximately 200 F. at atmospheric pressure, separating the resultant gasoline condensate from the vapor-gas mixture, and then rectifying the mixture in the absence of said condensate in a manner to condense said gasoline hydrocarbons boiling below approximately 2000 F. and to sharply separate the same from the incondensable gases.

4. A method for treating the vaporous and gaseous mixture produced in the cracking of hydrocarbon oils which comprises dephlegmating the mixture of vapors and gases to condense and separate therefrom fractions heavier than gasoline, then subjecting the mixture to partial condensation at a temperature above atmospheric to condense therefrom a heavy gasoline cut while retaining a lighter gasoline cut in vapor form, separating the condensed heavy gasoline cut.

from the vapor-gas mixture, and then rectifying the mixture in the absence of said condensed heavy gasoline cut to sharply separate and condense said lighter gasoline cut from the incondensable gases, and blending the condensed lighter gasoline cut with said condensed heavy gasoline cut.

5. A method for treatingthe vaporous and gaseous mixture produced in thecracking of hydrocarbon oils which comprises dephlegmating the mixture of vapors and gases to condense and separate therefrom fractions heavier than gasoline, then subjecting the mixture to partial condensation at a temperature above atmospheric, to condense therefrom a heavy gasoline cut while retaining a lighter gasoline cut in vapor form, separating the condensed heavy gasoline cut from the vapor-gas mixture, `in' introducing the mixture to the lower portion of a rectifying column which is heated at the bottom and cooled at the top and wherein the vapors and gases rise countercurrent to descending l condensate formed therein, and rectifying the mixture in said column in the absence of said condensed heavy gasoline cut to sharply separate and condense said lighter gasoline cut from the incondensable gases, and blendgaseous'mixture produced in the cracking of ing the condensed lighter gasoline cut with said condensed heavy gasoline cut.

6.- A method for treating the vaporous and hydrocarbon oils which comprises dephlegmating the mixture of vapors and gases to condense and separate therefrom fractions heavier than gasoline, subjecting the mixture to partial condensation in a manner to condense therefrom the gasoline ,hydrocarbons boiling above approximately 200 F. at atl mospheric pressure, while retaining in vapor form the gasoline hydrocarbons boiling below approximately 200 F. at atmospheric pressure, separating the resultant gasoline condensate from the vapor-gas mixture, and then rectifying the mixture in the vabsence of said condensate in a manner to condense densed gasolinehydrocarbons with said re- .,sultant gasoline condensate.

In testimony whereof I aflix my signature. JEAN D. SEGUY. 

